1. Field of the Invention
This invention relates to a row crop tillage unit for mounting from a pair of laterally spaced and rearwardly projecting lower hitch arms of a tractor. The tillage unit is mounted from the rear ends of the hitch arms for lateral shifting relative thereto and incorporates reversible motor structure for adjustably laterally shifting the tillage unit relative to the hitch arms. Crop row sensing structure is operatively associated with the reversible motor structure for actuation thereof in order to shift the tillage unit laterally of the hitch arms in the direction in which the sensing structure senses lateral displacement of a crop row relative to the longitudinal center axis of the associated tractor.
2. Description of Related Art
Various different forms of crop row position sensing control mechanisms heretofore have been utilized in conjunction with crop row tillage units shiftably supported from tractor mounted tool bars. In addition, crop row position sensing structure previously has been provided in operative association with a tractor steering mechanism and laterally shiftable cultivating structure previously has been provided for thinning row crops.
Examples of these various formes of cultivating devices are disclosed in U.S. Pat. Nos. 2,337,646, 2,753,781, 2,929,457, 2,981,355 and 3,955,626.
U.S. Pat. No. 3,955,626, dated May 11, 1976 to Clyde L. Taylor, discloses a tool bar mounted tillage or cultivator units shiftably mounted on the tool bar for adjustable lateral displacement of the units transversely of the associated tractor and along the transverse tool bar from which the tillage units are supported. In addition, the Taylor patent alos discloses center crop row position sensing structure operatively associated with the steering mechanism of the associated tractor whereby the tractor may be precisely steered along a center crop row for cultivation thereof.
However, the Taylor patent structure incorporated special tool bar structure and therefore does not enable a relatively inexpensive crop row tracking mechanism to be incorporated in a multirow tillage unit having a conventional tool bar structure.